IOS基础 Day-1手动内存管理

浏览数：23 / 时间：2015年06月11日

辞职回家打算自学IOS开发，就在借个地方记录一下

Day-1 手动内存管理

主要内容:release retain必须配对好，不然会占用内存慢慢积累导致错误

一旦内存占用超过40m 45m时分别发生警告，一旦超过120m 系统将kill你的app 发生闪退

主要要防止发生的问题:

1.野指针操作

2.内存泄漏

理解retain和assign的区别和 retain的原理

Main

  1  //
  2 //  main.m
  3 //  1-1内存管理
  4 //
  5 //  Created by k on 14-8-24.
  6 //  Copyright (c) 2014年 com.akleee.www. All rights reserved.
  7 //
  8 
  9 #import <Foundation/Foundation.h>
 10 #import "Person.h"
 11 #import "Car.h"
 12 void withParam(Person *p)
 13 {
 14     [p retain];
 15     NSLog(@"withParam : %@ ,retainCount : %lu",p.myName,(unsigned long)[p retainCount]);
 16     [p release];
 17 }
 18 
 19 void test1()
 20 {
 21     Person * p1=[[Person alloc ]init];
 22     
 23     NSLog(@"retainCount = %lu", (unsigned long)[p1 retainCount]);
 24     
 25     
 26     p1.myName=@"haha";
 27     
 28     NSLog(@"p1 : %@",p1);
 29     
 30     Person * p2 = [p1 retain];
 31     
 32     NSLog(@"retainCount = %lu", (unsigned long)[p1 retainCount]);
 33     
 34     
 35     p2.myName=@"gaga";
 36     
 37     NSLog(@"p1 : %@",p1);
 38     
 39     NSLog(@"p2 : %@",p2);
 40     
 41     withParam(p2);
 42 
 43     
 44     [p2 release];
 45     
 46     [p1 release];
 47     
 48     p1=nil;
 49     
 50     NSLog(@"%@",p1);//如果p1！＝nil 则会发生内存泄露
 51     
 52     NSLog(@"%lu", [p1 retainCount]);//nil 但是不报错
 53 }
 54 
 55 void test2()
 56 {
 57     Car * c1=[[Car alloc ] init:@"haha"];//初始化 带参数 的对象
 58 
 59     NSLog(@"%@",c1);
 60     
 61     [c1 release];
 62 }
 63 
 64 void test3(){
 65     Person * p1=[[Person alloc]init:@"ak"];
 66     
 67     Car * c1= [[Car alloc]init:@"雪弗兰"];
 68     
 69     [p1 setCar:c1];
 70     
 71     [p1 run];
 72     
 73     //1
 74     // NSLog(@"p1 retainCount : %lu", [p1 retainCount]);
 75     //1
 76     //NSLog(@"c1 retainCount : %lu", [c1 retainCount]);
 77     
 78       [c1 release];
 79   
 80     [p1 release];
 81 }
 82 
 83 void test4()
 84 {
 85     //测试property的retain
 86     Person * p1=[[Person alloc]init];
 87 
 88     Car * c1=[[Car alloc]init];
 89     
 90     Car * c2= [[Car alloc]init];
 91     
 92     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
 93 
 94     
 95     p1.car=c1;
 96     
 97     
 98     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
 99     
100     
101     p1.car=c2;
102     
103     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
104     
105     NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);
106     
107     [c1 release];
108     [c2 release];
109     [p1 release];
110 }
111 
112 void test5()
113 {
114     Person * p1=[[Person alloc]init];
115     
116     Car * c1=[[Car alloc]init];
117     
118     Car * c2= [[Car alloc]init];
119     
120     //1
121     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
122     //1
123     NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);
124     
125 
126     
127     [p1 setCar2:c1];
128     
129     //2
130     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
131     
132     
133     [p1 setCar2:c2];
134     
135     //1
136     NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);
137     
138     //2
139     NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);
140     
141     
142     
143     NSString * s1=@"aaa";
144     
145    // NSString * s2=@"bbb";
146     
147     NSLog(@"s1:%lu",(unsigned long)[s1 retainCount]);
148     
149     [p1 setMyName:s1];
150     
151     NSLog(@"s1:%lu",(unsigned long)[s1 retainCount]);
152     
153     [c1 release];
154     [c2 release];
155     [p1 release];
156 
157 }
158 int main(int argc, const char * argv[])
159 {
160 
161     @autoreleasepool {
162         
163        // test1();
164        // test2();
165        // test3();
166         test4();
167         //test5();
168     }
169     return 0;
170 }

View Code

Person.h

 1 //
 2 //  Person.h
 3 //  1 基础知识
 4 //
 5 //  Created by k on 14-8-24.
 6 //  Copyright (c) 2014年 com.akleee.www. All rights reserved.
 7 //
 8 
 9 #import <Foundation/Foundation.h>
10 #import "Car.h"
11 
12 @interface Person : NSObject
13 @property (nonatomic,assign , readwrite ) NSString * myName  ;
14 @property (nonatomic,retain,readwrite) Car * car;
15 -(instancetype)init:(NSString *) Name;
16 -(void) speakMyName;
17 -(void)setCar:(Car *) car;
18 -(void) run;
19 
20 
21 
22 -(void)setCar2:(Car*)car2;
23 @end
24

View Code

person.m

 1 //
 2 //  Person.m
 3 //  1 基础知识
 4 //
 5 //  Created by k on 14-8-24.
 6 //  Copyright (c) 2014年 com.akleee.www. All rights reserved.
 7 //
 8 
 9 #import "Person.h"
10 
11 @implementation Person
12 {
13     Car * _car2;
14 }
15 
16 - (instancetype)init:(NSString *) Name
17 {
18     self = [super init];
19     if (self) {
20         _myName=Name;
21     }
22     return self;
23 }
24 
25 -(void)speakMyName{
26 
27     NSLog(@"大家好我的名字叫%@",_myName);
28     
29 }
30 
31 
32 
33 -(void)setCar2:(Car*)car2
34 {
35   if(_car2!=car2)
36   {
37       [_car2 release];
38       _car2=car2;
39       [car2 retain ];
40   }
41 }
42 
43 -(void)run{
44 
45     NSLog(@"%@ 驾驶着 %@",_myName,_car.carName);
46     
47 }
48 
49 - (NSString *)description
50 {
51     return [NSString stringWithFormat:@"this is Person,myName=%@", _myName];
52 }
53 
54 - (void)dealloc
55 {
56     [_car2 release];
57     [super dealloc];
58     NSLog(@"Person对象被销毁");
59 }
60 @end

View Code

Car.h

 1 //
 2 //  Car.h
 3 //  1 基础知识
 4 //
 5 //  Created by k on 14-8-24.
 6 //  Copyright (c) 2014年 com.akleee.www. All rights reserved.
 7 //
 8 
 9 #import <Foundation/Foundation.h>
10 
11 @interface Car : NSObject
12 
13 @property (nonatomic,assign,readwrite) NSString * carName;
14 - (instancetype)init:(NSString *)Name;
15 
16 -(void)run;
17 @end

View Code

Car.m

 1 //
 2 //  Car.m
 3 //  1 基础知识
 4 //
 5 //  Created by k on 14-8-24.
 6 //  Copyright (c) 2014年 com.akleee.www. All rights reserved.
 7 //
 8 
 9 #import "Car.h"
10 
11 @implementation Car
12 
13 - (instancetype)init:(NSString *)Name
14 {
15     self = [super init];
16     if (self) {
17         _carName=Name;
18     }
19     return self;
20 }
21 -(void)run
22 {
23 
24     NSLog(@"%@ is Running",_carName);
25 }
26 - (NSString *)description
27 {
28     return [NSString stringWithFormat:@"carName : %@", _carName];
29 }
30 - (void)dealloc
31 {
32     [super dealloc];
33     NSLog(@"Car %@ 被销毁",_carName);
34 }
35 @end